[wxqc] Vantage Pro Barometer problems

[Steve]

The altimeter issue was a well known problem, and the fix is in the 
WeatherLink software, not the firmware. With the fix, the WeatherLink 
software takes the sea level pressure obtained from the data logger, and 
from that it calculates the altimeter value for sending to CWOP. This is 
mentioned in the revision history for WeatherLink. It was added in version 
5.7. This is a very important fix.

The firmware fix (appearing in 1.6) had to do with hourly anomalies in the 
console's sea level pressure. This problem was an artifact of the internal 
algorithm inside the console that calculates the sea level pressure from the 
sensor pressure, elevation, temperature and humidity. I'm pretty familiar 
with that problem too, because another VP owner and I who both live at 
elevation and noticed the problem pointed it out to Davis, and we provided 
Davis with information on how to fix the problem in their algorithm.

So having the latest firmware AND WeatherLink software are both important in 
submitting good pressure data to CWOP.

Steve
SoftWx

----- Original Message ----- 
From: "Rex Pirkle" <k8cyj at arrl.net>
To: <wxqc at lists.gladstonefamily.net>
Sent: 04/11/2008 7:15 PM
Subject: Re: [wxqc] Vantage Pro Barometer problems


> The Davis VP/VP2 barometer problems that Steve mentions below are
> firmware issues, not resolved by WeatherLink software changes.   Davis
> has several different firmware revisions published; each depends on the
> datalogger type and your console firmware date.  The details are here:
>
>
> http://www.davisnet.com/support/weather/software_frmwr.asp
>
> Since updating firmware, my barometer tracks very well with MADIS -- no
> need to enter 'fake' elevations, just a slight offset entered by the
> 'owners manual' procedure.  Readings were very inconsistent prior to the
> update.
>
> Rex Pirkle
> AR863/K8CYJ-5
>
> ----- Original Message ---
>
>
> The problem had to do with the fact that the Vantage Pro station reports
> Sea
> Level Pressure (SLP) but CWOP wants altimeter for the pressure. The two
> values are not the same, and the difference between them increases with
> the
> elevation of your station location. However, that should no longer be an
>
> issue if people are using the latest version of WeatherLink. Davis
> recently
> made a change so that WeatherLink calculates the proper altimeter value
> and
> sends that to CWOP. Several other software programs that connect to the
> Vantage Pro also will correctly calculate and send the altimeter value,
> although you may need to enable that feature in the configuration
> screen.
> So, for most people, there should no longer be any need to do goofy
> workarounds for the VP pressure to get good data to CWOP.
>
> Steve
> SoftWx
>
>
>
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